In general, a reactor includes a coil and a magnetic core and forms inductance by bending the coil around the magnetic core. According to the related art, reactors are used in boosting circuits, inverter circuits, active filter circuits and the like. In particular, in reactors used in boosting circuits for vehicles, in order to obtain a high degree of inductance in a high current region, two coils are commonly connected in parallel such that current flowing in the coils flows in a forward direction. However, since may be difficult to consecutively produce the first coil part and the second coil part, the first coil part and the second coil part may be separately produced and subsequently connected to each other by a method such as a soldering method or the like. Since such a production method requires two types of coil part and needs to include a connection process using soldering or the like, a process for insulation processing in a connection portion, a process for inspecting electrical characteristics in the associated connection portion, a process for inspecting electrical insulating characteristics, and the like, the number of production processes may be increased, mass productivity may be deteriorated and at the same time, costs required therefor may be increased. In addition, a product produced by the method described above has a connection portion and further, the connection portion is disposed outwardly of the coil, which may deteriorate performance of the product such as degrading reliability, generating quality deviations, and the like.
Alternatively, a method of consecutively forming the first coil part and the second coil part without a connection process such as soldering or the like, but in which the second coil part is bent at an angle of 180° with respect to the first coil part to form a bent connection portion exists. However, stress concentration may be disadvantageously generated in the bent connection portion produced by this method.
Alternatively, a method of forming first and second coil parts such that a bent portion formed by bending a single flat coil from respective ends thereof in a length direction is stacked in an angular tube shape exists. However, the coil formation method further requires a length measuring process for measuring a length of a connection portion immediately before the completion of a second coil after a first coil has been completed while the first coil is formed before the formation of the second coil, a length dividing process for dividing the measured length of the connection portion into a length thereof for a preset interval between both coils and a length thereof for adjusting the flat coil set in the second coil, and a final bending process for installing an offset portion in one side of an edge of the bent portion in the second coil so as to correspond to the divided length, and simultaneously, setting the interval between the both coils. Consequently, since the coil formation method includes a large number or processes and particularly, further includes a process for measuring a length of the remaining wire in a manufacturing process of a connection coil, it may be disadvantageous in terms of efficiency and costs in a manufacturing method.